Community-serving research addressing climate change impacts on vector-borne diseases.

The impacts of climate change on vector-borne diseases are uneven across human populations. This pattern reflects the effect of changing environments on the biology of transmission, which is also modulated by social and other inequities. These disparities are also linked to research outcomes that could be translated into tools for transmission reduction, but are not necessarily actionable in the communities where transmission occurs. The transmission of vector-borne diseases could be averted by developing research that is both hypothesis-driven and community-serving for populations affected by climate change, where local communities interact as equal partners with scientists, developing and implementing research projects with the aim of improving community health. In this Personal View, we share five principles that have guided our research practice to serve the needs of communities affected by vector-borne diseases.

Characterization of Leishmania spp. Causing Cutaneous Lesions with a Negative Parasitological Diagnosis in Panama.

A total of 123 DNA samples from Panamanian patients with cutaneous leishmaniasis (CL) lesions were evaluated. These samples were previously confirmed with CL by a specific KDNA-Viannia PCR but had a negative parasitological diagnosis (Group A). Epidemiological variables, such as age, sex, geographic origin, evolution time, and the number and location of the lesions, were analyzed. No significant differences (p < 0.05) were found when these variables were evaluated against a control panel of 123 CL lesion samples from CL patients with positive parasitological diagnoses (Group B). Of the 123 samples (Group A), 67% (82/123) gave positive results when re-analyzed by PCR-hsp70. An analysis of 69 of these samples via PCR-hsp70-RFLP showed that 59.4% (41/69) of the found restriction patterns corresponded to Leishmania (Viannia) panamensis and 40.6% (28/69) to Leishmania (Viannia) guyanensis. Finally, the sequence and phylogenetic analysis of 32 of the samples confirmed the species in 21 (65.6%, 21/32) samples, originally characterized as L. (V.) panamensis. However, 11 samples (34.4%, 11/32), initially identified via RFLP-Hsp70 as L. (V.) guyanensis, matched the sequence of a genetic variant known as Leishmania sp.1. These results point out the species/genetic variants of Leishmania in the case of CL lesions with an apparently low parasite load.

First report of imported canine visceral leishmaniasis cases in Panama, Central America: Public health implications.

According to the last leishmaniasis report from the Pan American Health Organization (2021) so far Panama is considered free of visceral leishmaniasis (VL). Although the presence of potential vectors and reservoirs involved in the VL transmission cycle have been described in some rural regions of the country, no cases have been reported in humans and domestic or wild animals. Dogs play an important role in the urban transmission of VL; therefore, it is important to detect possible cases of canine visceral leishmaniasis (CVL) in the country. In this sense,this study reports for the first time the Leishmania (Leishmania) infantum infection in imported dogs in Panama. Eleven dogs with clinical suspicion of CVL were evaluated by parasitological (bone marrow aspirate smear), serological (indirect immunofluorescence and/or reference immunochromatographic rapid test) and molecular tests (conventional PCR). The dogs included in this study were analyzed during the period from 2013 to 2020. All dogs presented clinical manifestations compatible with CVL. The samples were initially evaluated by smears and/or rapid serological tests by private practice veterinarians, and later confirmed by serological and/or molecular tests at the national reference laboratory for Leishmania diagnosis. The diagnosis was confirmed in 5/11 dogs by serological, parasitological and/or conventionals PCR targeting kDNA minicircle and Hsp70 gene. Leishmania (L.) infantum species was identified in 3/5 dogs by PCR-RFLP and by sequencing Hsp70-PCR products. This study evidenced the need to increase awareness of private practitioners as well as public health veterinarians on visceral leishmaniasis (VL), and to consider this parasitosis in the differential diagnosis of dogs with clinical and epidemiological characteristics compatible with the disease.

Genetic Diversity of Trypanosoma cruzi in Panama Inferred by Multi-locus Sequence Typing of Mitochondrial Genes.

The objective of this study was to provide information on Trypanosoma cruzi genetic diversity among isolates obtained from different biological sources circulating in endemic areas of Panama. Initial discrete typing units (DTUs) assignment was performed evaluating three single locus molecular markers (mini-exon, heat shock protein 60 and glucose-6-phosphate isomerase genes). Further diversity within TcI lineages was explored using a multi-locus sequence typing approach with six maxicircle genes. Haplotype network analysis and evolutionary divergency estimations were conducted to investigate the genetic relatedness between Panamanian TcI isolates and isolates from different endemic regions in the Americas. Our molecular approach validated that TcI is the predominant DTU circulating in Panama across different hosts and vector species, but also confirmed the presence of TcIII and TcVI circulating in the country. The phylogenetic tree topography for most Panamanian TcI isolates displayed a high level of genetic homogeneity between them. The haplotype network analysis inferred a higher genetic diversity within Panamanian TcI isolates, displaying eight different haplotypes circulating in endemic regions of the country, and revealed geographical structuring among TcI from different endemic regions in the Americas. This study adds novelty on the genetic diversity of T. cruzi circulating in Panama and complements regional phylogeographic studies regarding intra-TcI variations.

Surveillance and genotype characterization of zoonotic trypanosomatidae in Didelphis marsupialis in two endemic sites of rural Panama.

Didelphis marsupialis has been reported as a competent reservoir for trypanosomatid parasites infections. The aim of this study was to measure Trypanosoma cruzi, T. rangeli, and Leishmania spp. infection rates and to characterize discrete typing units (DTUs) of T. cruzi in D. marsupialis from two Chagas disease endemic sites in Panama. Blood from 57 wild-caught D. marsupialis were examined from two rural communities, Las Pavas (N = 18) and Trinidad de las Minas (N = 39). Twenty-two (38.60%) opossums were positive for flagellates by general hemoculture. T. cruzi infection was confirmed by positive hemoculture and/or kDNA based PCR performed in 31/57 (54.39%) blood samples from opossums. T. rangeli infection was confirmed by hemoculture and/or TrF/R2-Primer PCR assay applied on 12/57 (21.05%) blood samples. Nine (15.79%) D. marsupialis harbored T. cruzi/T. rangeli coinfections. All opossums tested negative for Leishmania spp. by PCR assays based on kDNA and HSP70 gene amplification. There was a significant association between T. cruzi infection and site (Fisher exact test, p = 0.02), with a higher proportion of T. cruzi infected opossums in Las Pavas (77.78%, n = 14/18) compared to Trinidad de las Minas (43.59%, n = 17/39). A significant association was found between habitat type and T. cruzi infection in opossums across both communities, (X2 = 6.91, p = 0.01, df = 1), with a higher proportion of T. cruzi infection in opossums captured in forest remnants (76%, 19/25) compared to peridomestic areas (37.5%, 12/32). T. rangeli detection, but not T. cruzi detection, may be improved by culture followed by PCR. TcI was the only DTU detected in 22 T. cruzi samples using conventional and real-time PCR. Eight T. rangeli positive samples were characterized as KP1(-)/lineage C. Trypanosome infection data from this common synanthropic mammal provides important information for improved surveillance and management of Chagas disease in endemic regions of Panama.

Factores de riesgo asociados con la leishmaniasis cutánea en dos comunidades rurales de Panamá Oeste

Introducción: La leishmaniasis cutánea (LC) es una enfermedad zoonótica endémica en Panamá. Su agente causal son protozoarios del género Leishmania y la transmiten insectos flebotominos. Objetivo: Evaluar los factores de riesgos asociados con la LC y la diversidad de flebotominos en dos comunidades rurales de Panamá Oeste. Metodología: Se seleccionaron dos comunidades endémicas para LC: Trinidad de las Minas (TM), de alta incidencia y Las Pavas (LP), de baja incidencia. Los factores de riesgo asociados con la LC fueron evaluados mediante una encuesta aplicada a100 personas (TM: n=50; LP: n=50). Se colectaron flebotominos con trampas CDC durante tres noches consecutivas en temporada lluviosa y seca. Resultados: La mayoría de las personas confirmó conocer sobre la LC (TM: 96% y LP: 68%). No se encontraron diferencias significativas entre las características sociodemográficas, estructura de las viviendas, composición del peridomicilio y abundancia/diversidad de animales domésticos en ambas comunidades. El reporte de perezosos cercanos al peridomicilio fue mayor en TM (70%) vs LP (32%). La especie de flebotomino antropofílica más abundante durante la temporada seca fue Lutzomyia gomezi (TM: 40.1% y LP: 10.4%). Durante la temporada lluviosa fue Nyssomyia trapidoi (43.4%) en TM y Psychodopygus panamensis (75.7%) en LP. Las especies zoofílicas más comunes en ambas comunidades fueron Trichopygomyia triramula y Pressatia dysponeta. Conclusión: La mayor incidencia de LC en TM podría estar condicionada a su ecología montañosa, con una cobertura boscosa cercana más extensa y una mayor frecuencia de mamíferos reservorios silvestres. Se confirmó la presencia de vectores de LC en el peridomicilio de ambas comunidades. (provisto por Infomedic International)

Introduction: Cutaneous leishmaniasis (CL) is a zoonotic disease endemic in Panama. Its causal agent are protozoa of the genus Leishmania and is transmitted by phlebotomine sandflies. Objective: To evaluate the risk factors associated with CL and the diversity of phlebotomine sandflies in two rural communities in western Panama. Methodology: Two CL endemic communities were selected: Trinidad de las Minas (TM), with high incidence and Las Pavas (LP), with low incidence. The risk factors associated with CL were assessed by means of a survey applied to 100 people (TM: n=50; LP: n=50). Phlebotomine sandflies were collected with CDC traps during three consecutive nights in rainy and dry season. Results: The majority of people confirmed knowledge about CL (TM: 96% and LP: 68%). No significant differences were found between sociodemographic characteristics, housing structure, peridomicile composition and abundance/diversity of domestic animals in both communities. The report of sloths near the peridomicile was higher in TM (70%) vs LP (32%). The most abundant anthropophilic phlebotomine species during the dry season was Lutzomyia gomezi (TM: 40.1% and LP: 10.4%). During the rainy season it was Nyssomyia trapidoi (43.4%) in TM and Psychodopygus panamensis (75.7%) in LP. The most common zoophilic species in both communities were Trichopygomyia triramula and Pressatia dysponeta. Conclusion: The higher incidence of CL in TM could be conditioned to its mountainous ecology, with a more extensive nearby forest cover and a higher frequency of wild mammal reservoirs. The presence of CL vectors in the peridomicile of both communities was confirmed. (provided by Infomedic International)

Natural malaria infection in anophelines vectors and their incrimination in local malaria transmission in Darién, Panama.

BACKGROUND: More than 85% of the malaria cases in Panama occur in poor, rural and indigenous regions like Darien Province. Vector diversity, infection rate and spatial distribution are important entomological parameters of malaria transmission dynamics. Their understanding is crucial for the development of effective disease control strategies. The objective of this study was to determine the composition of Anopheles species, their natural infection rate and their geographic distribution to better understand the malaria transmission dynamics in Darién, Panama. METHODS: Anophelines mosquitoes were captured during the rainy and dry season of 2016. We selected five communities where adult anophelines were collected using CDC light-traps, and through protective human-baited traps. Detection of natural infection and Plasmodium genotype were detected via nested PCR through the amplification of ssrRNA and the circumsporozoite protein gene (csp), respectively. RESULTS: A total of 1,063 mosquitoes were collected mosquitoes were collected for the detection of natural infection with Plasmodium spp. Nine Anophelines species were identified, with the predominant species being: An. (Nys.) darlingi (45.0%) and An. (Nys.) albimanus (42.6%). Natural infection in An. (Nys.) albimanus with P. vivax was detected in one mosquito pool from the community Pueblo Tortuga (0.6%), three from Marraganti (1.7%), two from Bajo Chiquito (1.1%) and three pools from Alto Playona 3 (1.7%). For An. (Nys.) darlingi mosquitoes, we detected seven positive pools from the community Bajo Chiquito (4.0%), two pools from Marraganti (1.1%) and two pools from Alto Playona (1.1%). The P. vivax allelic variant VK210 was detected in infected mosquitoes. CONCLUSION: The results from this study provide new information on the transmission dynamics associated with anophelines vectors in the Darién region. This is the first report of natural P. vivax infection in An. (Nys.) darlingi and its incrimination as a potential malaria vector in this region of Panama. Additional studies are necessary to expand our knowledge and determine crucial parameters in malaria transmission in Darién, which in turn will aid the National Malaria Program in attaining an adequate malaria control strategy towards malaria elimination.

Evaluation of cytochrome b sequence to identify Leishmania species and variants: the case of Panama.

BACKGROUND: The genetic heterogeneity of Leishmania parasites is a major factor responsible for the wide variety of Leishmania-associated manifestations. Consequently, understanding the genetic make-up of Leishmania species using suitable molecular markers is an important component of realising local and regional scale disease risk. The cytochrome b (cytb) is frequently used to type New World Leishmania species. However, its potential to discriminate Leishmania species and variants requires further evaluation. OBJECTIVES: To explore the capacity of cytb gene to identify New World Leishmania species and variants and to develop an approach able to type local Leishmania species and variants. METHODS: We retrieved 360 partial and complete Leishmania cytb gene sequences publicly available in GenBank database to study all single nucleotide polymorphisms (SNPs) across the cytb gene that differentiate New World Leishmania species. This information was used to develop an approach based upon the polymorphisms found in a DNA segment of 948bp. We also compared the typing results found with this technique with the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) profiling obtained using HSP70 gene as target. One hundred Panamanian isolates were used to both typed Leishmania species and assess local genetic variability. FINDINGS: We found complete agreement between our cytb approach and the PCR-RFLP profiling method based on HSP70 for Leishmania species identification. Ninety-two isolates were identified as L. panamensis, although other Viannia species were found circulating at a lower frequency. Three L. panamensis haplotypes were identified in Panamanian provinces. We also provide an initial report of L. guyanensis haplotypes circulating in Panama. MAIN CONCLUSIONS: Cytb gene sequence encompasses key main SNPs that aid to identify Leishmania species. The cytb approach developed with this information was able to identify and assess genetic variability of local Leishmania species found in this study.

Repeat-Driven Generation of Antigenic Diversity in a Major Human Pathogen, Trypanosoma cruzi.

Trypanosoma cruzi, a zoonotic kinetoplastid protozoan parasite, is the causative agent of American trypanosomiasis (Chagas disease). Having a very plastic, repetitive and complex genome, the parasite displays a highly diverse repertoire of surface molecules, with pivotal roles in cell invasion, immune evasion and pathogenesis. Before 2016, the complexity of the genomic regions containing these genes impaired the assembly of a genome at chromosomal level, making it impossible to study the structure and function of the several thousand repetitive genes encoding the surface molecules of the parasite. We here describe the genome assembly of the Sylvio X10/1 genome sequence, which since 2016 has been used as a reference genome sequence for T. cruzi clade I (TcI), produced using high coverage PacBio single-molecule sequencing. It was used to analyze deep Illumina sequence data from 34 T. cruzi TcI isolates and clones from different geographic locations, sample sources and clinical outcomes. Resolution of the surface molecule gene distribution showed the unusual duality in the organization of the parasite genome, a synteny of the core genomic region with related protozoa flanked by unique and highly plastic multigene family clusters encoding surface antigens. The presence of abundant interspersed retrotransposons in these multigene family clusters suggests that these elements are involved in a recombination mechanism for the generation of antigenic variation and evasion of the host immune response on these TcI strains. The comparative genomic analysis of the cohort of TcI strains revealed multiple cases of such recombination events involving surface molecule genes and has provided new insights into T. cruzi population structure.

Molecular Identification of Parasites Causing Cutaneous Leishmaniasis in Panama.

Isolates from 475 cutaneous leishmaniasis (CL) patients from three endemic regions were studied by three typing techniques. The molecular analysis from lesion scrapings based on hsp70 PCR-restriction fragment length polymorphism (RFLP) showed that 78.1% (371/475) restriction patterns corresponded to Leishmania (Viannia) panamensis, 19% (90/475) to Leishmania (Viannia) guyanensis, and 3.0% (14/475) to Leishmania (Viannia) braziliensis. Promastigotes isolated by culture from lesions of 228 patients (48.0%, 228/475) were identified by multi-locus enzyme electrophoresis. Of them, 95.2% (217/228) were typified as L. (V.) panamensis, 1.3% (3/228) as L. (V.) guyanensis, 2.2% (5/228) as L. (V.) braziliensis, and 1.3% (3/228) as hybrids (L. [V.] braziliensis/L. [V.] panamensis). However, a partial sequencing analysis of the hsp70 gene from 77 selected samples showed 16.9% (13/77) typified as L. (V.) panamensis, 68.8% (53/77) as Leishmania (V.) sp., 1, 3.9% (3/77) as L. (V.) guyanensis, 1.3% (1/77) as L. (V.) braziliensis outlier, 2.6% (2/77) as Leishmania (Viannia) naiffi, 2.6% as (2/77) Leishmania (V.) sp., and 2 and 3.9% (3/77) hybrid isolates of L. (V.) braziliensis/L. (V.) guyanensis. These results confirm L. (V.) panamensis as the predominant species and cause of CL lesions in Panama and that L. (V.) guyanensis, L. (V.) braziliensis, and L. (V.) naiffi are circulating to a lower degree. Furthermore, the determination of parasite isolates belonging to atypical clusters and hybrid isolates suggests the circulation of genetic variants with important implications for the epidemiology and clinical follow-up of CL in Panama. No evidence of the existence of parasites of the Leishmania (Leishmania) mexicana complex in Panamanian territory was found in this study.

Evaluation of cytochrome b sequence to identify Leishmania species and variants: the case of Panama

BACKGROUND The genetic heterogeneity of Leishmania parasites is a major factor responsible for the wide variety of Leishmania-associated manifestations. Consequently, understanding the genetic make-up of Leishmania species using suitable molecular markers is an important component of realising local and regional scale disease risk. The cytochrome b (cytb) is frequently used to type New World Leishmania species. However, its potential to discriminate Leishmania species and variants requires further evaluation. OBJECTIVES To explore the capacity of cytb gene to identify New World Leishmania species and variants and to develop an approach able to type local Leishmania species and variants. METHODS We retrieved 360 partial and complete Leishmania cytb gene sequences publicly available in GenBank database to study all single nucleotide polymorphisms (SNPs) across the cytb gene that differentiate New World Leishmania species. This information was used to develop an approach based upon the polymorphisms found in a DNA segment of 948bp. We also compared the typing results found with this technique with the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) profiling obtained using HSP70 gene as target. One hundred Panamanian isolates were used to both typed Leishmania species and assess local genetic variability. FINDINGS We found complete agreement between our cytb approach and the PCR-RFLP profiling method based on HSP70 for Leishmania species identification. Ninety-two isolates were identified as L. panamensis, although other Viannia species were found circulating at a lower frequency. Three L. panamensis haplotypes were identified in Panamanian provinces. We also provide an initial report of L. guyanensis haplotypes circulating in Panama. MAIN CONCLUSIONS Cytb gene sequence encompasses key main SNPs that aid to identify Leishmania species. The cytb approach developed with this information was able to identify and assess genetic variability of local Leishmania species found in this study.

Plasmodium falciparum Genetic Diversity in Panamá Based on glurp, msp-1 and msp-2 Genes: Implications for Malaria Elimination in Mesoamerica.

Panamá, together with all the nations in Mesoamerica, has committed to eliminate malaria from the region by 2020. As these countries approach malaria elimination and local transmission decreases, an active molecular surveillance to identify genotypes circulating along the border areas is particularly needed to accurately infer infection origin, drug resistance and disease propagation patterns in the region. This study evaluated the genetic diversity and allele frequencies of msp-1, msp-2 and glurp genes using different molecular analyses (nested PCR, PCR-restriction fragment length polymorphism (RFLP) and sequencing) from 106 autochthonous and imported P. falciparum isolates collected from different endemic areas in Panamá between 2003 and 2019. We also explored if P. falciparum genotypes assessed with these molecular markers were associated with relevant malaria epidemiological parameters using a multiple correspondence analysis. A strong association of certain local haplotypes with their geographic distribution in endemic areas, but also with parasite load and presence of gametocytes, was evidenced. Few multiclonal infections and low genetic diversity among locally transmitted P. falciparum samples were detected, consequent with the low transmission intensity of this parasite in Panamá, a pattern likely to be extended across Mesoamerica. In addition, several imported cases were genetically dissimilar to local infections and representative of more diverse extra-continental lineages.

Landscape disturbance impacts on Attalea butyracea palm distribution in central Panama.

BACKGROUND: Increased Attalea butyracea palm propagation, notable for its role as key habitat for the primary Chagas disease vector in Panama, has been linked to landscape disturbance in single-palm observations in this region. Close proximity of these palms to human dwellings is proposed to increase risk of Chagas disease transmission from sylvatic transmission cycles to domestic transmission involving human populations. This study examines the relationship between landscape disturbance and mature A. butyracea spatial distribution, density, and proximity to human populations and vector and reservoir species' movement corridors at a regional scale in a 300 km2 heterogeneous tropical landscape in central Panama. METHODS: We remotely identified the locations of over 50,000 mature A. butyracea palms using high-resolution WorldView2 satellite imagery. A local Getis-Ord Gi* spatial analysis identified significant clusters of aggregated palms. Associations between palm and cluster abundance and a landscape disturbance gradient, derived from official Panama land cover data, were tested using Chi-square tests for Homogeneity and Z-test for proportions. Kruskall-Wallis non-parametric analysis of variance tests were run to assess whether palm cluster area varied by disturbance level, or whether disturbance was associated with proximity of palms and palm clusters to susceptible populations or vector movement corridors. RESULTS: Our findings indicate a regional relationship between landscape disturbance and A. butyracea occurrence. We observe a significant increase in both individual and clustered A. butyracea in secondary forest, but a reduction of palms in agricultural settings. We do not detect evidence of any reduction in abundance of palms in residential settings. The majority of residential and commercial buildings in our study area are within vector flight distance of potential vector habitat in palm crowns. CONCLUSIONS: We observe probable anthropogenic elimination of A. butyracea palms in agricultural, but not residential, settings. Even in heavily deforested regions, significant concentrations of mature palms remain in close proximity to human establishments.

Long-term transmission patterns and public health policies leading to malaria elimination in Panamá.

BACKGROUND: The present study provides a countrywide perspective of the malaria situation in Panamá over a long-term framework, with the purpose of identifying historical malaria resurgence events and their potential causes. METHODS: A descriptive-ecological study was conducted by analysing demographic and epidemiological annual malaria time series data in Panamá (1884-2019) using several data sources. Malaria intensity indicators were calculated during the study period. The effects of El Niño Southern Oscillation on malaria transmission were also analysed using a retrospective analysis of malaria cases between 1957 and 2019. RESULTS: Several factors were identified responsible for malaria resurgence in Panamá, mostly related with Malaria Control Programme weakening. During the past 20 years (2000-2019) malaria has progressively increased in prevalence within indigenous settlements, with a predominance of male cases and a high proportion (15% of total cases) in children less than 5 years old. During this period, a significant and increasing proportion of the Plasmodium falciparum cases were imported. Retrospective analysis (1957-2019) evidenced that ENSO had a significant impact on malaria transmission dynamics in Panamá. CONCLUSIONS: Data analysis confirmed that although authorities have been successful in focalizing malaria transmission in the country, there are still neglected issues to be solved and important intercultural barriers that need to be addressed in order to achieve elimination of the disease by 2022. This information will be useful for targeting strategies by the National Malaria Elimination Programme.

Population genetics of two chromatic morphs of the Chagas disease vector Rhodnius pallescens Barber, 1932 in Panamá.

Rhodnius pallescens is the principal vector of Chagas disease in Panama. Recently a dark chromatic morph has been discovered in the highlands of Veraguas Province. Limited genetic studies have been conducted with regards to the population structure and dispersal potential of Triatominae vectors, particularly in R. pallescens. Next generation sequencing methods such as RADseq and complete mitochondrial DNA (mtDNA) genome sequencing have great potential for examining vector biology across space and time. Here we utilize a RADseq method (3RAD), along with complete mtDNA sequencing, to examine the population structure of the two chromatic morpho types of R. pallescens in Panama. We sequenced 105 R. pallescens samples from five localities in Panama. We generated a 2216 SNP dataset and 6 complete mtDNA genomes. RADseq showed significant differentiation among the five localities (FCT = 0.695; P = .004), but most of this was between localities with the dark vs. light chromatic morphs (Veraguas vs. Panama Oeste). The mtDNA genomes showed a 97-98% similarity between dark and light chromatic morphs across all genes and a 502 bp insert in light morphs. Thus, both the RADseq and mtDNA data showed highly differentiated clades with essentially no gene flow between the dark and light chromatic morphs from Veraguas and central Panama respectively. We discuss the growing evidence showing clear distinctions between these two morpho types with the possibility that these are separate species, an area of research that requires further investigation. Finally, we discuss the cost-effectiveness of 3RAD which is a third of the cost compared to other RADseq methods used recently in Chagas disease vector research.

Correction: Synanthropic Mammals as Potential Hosts of Tick-Borne Pathogens in Panama.

[This corrects the article DOI: 10.1371/journal.pone.0169047.].

Study of the epidemiological behavior of malaria in the Darien Region, Panama. 2015-2017.

BACKGROUND: Malaria is endemic in Darién and an assessment of the different factors affecting its epidemiology is crucial for the development of adequate strategies of surveillance, prevention, and disease control. The objective of this study was to determine the main characteristics of the epidemiological behavior of malaria in the Darien region. METHODS: This research was comprised of a retrospective analysis to determine the incidence and malaria distribution in the Darien region from 2015 to 2017. We evaluated malaria indicators, disease distribution, incidence (by age group and sex), diagnostic methods, treatment, and control measures. In addition, we examined the cross-border migration activity and its possible contribution to the maintenance and distribution of malaria. RESULTS: During the period of 2015-2017, we examined 41,141 thick blood smear samples, out of which 501 tested positive for malaria. Plasmodium vivax was responsible for 92.2% of those infections. Males comprised 62.7% of the total diagnosed cases. Meanwhile, a similar percentage, 62.7%, of the total cases were registered in economically active ages. The more frequent symptoms included fever (99.4%) and chills (97.4%), with 53.1% of cases registering between 2,000 and 6,000 parasites/µl of blood. The annual parasitic incidence (API) average was 3.0/1,000 inhabitants, while the slide positivity rate (SPR) was 1.2% and the annual blood examination rate (ABER) 22.5%. In Darién there is a constant internal and cross-border migration movement between Panama and Colombia. Malaria control measures consisted of the active and passive search of suspected cases and of the application of vector control measures. CONCLUSION: This study provides an additional perspective on malaria epidemiology in Darién. Additional efforts are required to intensify malaria surveillance and to achieve an effective control, eventually moving closer to the objective of malaria elimination. At the same time, there is a need for more eco-epidemiological, entomological and migratory studies to determine how these factors contribute to the patterns of maintenance and dissemination of malaria.

Regional biogeography of microbiota composition in the Chagas disease vector Rhodnius pallescens.

BACKGROUND: Triatomine bugs are vectors of the protozoan parasite Trypanosoma cruzi, which causes Chagas disease. Rhodnius pallescens is a major vector of Chagas disease in Panama. Understanding the microbial ecology of disease vectors is important in the development of vector management strategies that target vector survival and fitness. In this study we examined the whole-body microbial composition of R. pallescens from three locations in Panama. METHODS: We collected 89 R. pallescens specimens using Noireau traps in Attalea butyracea palms. We then extracted total DNA from whole-bodies of specimens and amplified bacterial microbiota using 16S rRNA metabarcoding PCR. The 16S libraries were sequenced on an Illumina MiSeq and analyzed using QIIME2 software. RESULTS: We found Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes to be the most abundant bacterial phyla across all samples. Geographical location showed the largest difference in microbial composition with northern Veraguas Province having the most diversity and Panama Oeste Province localities being most similar to each other. Wolbachia was detected in high abundance (48-72%) at Panama Oeste area localities with a complete absence of detection in Veraguas Province. No significant differences in microbial composition were detected between triatomine age class, primary blood meal source, or T. cruzi infection status. CONCLUSIONS: We found biogeographical regions differ in microbial composition among R. pallescens populations in Panama. While overall the microbiota has bacterial taxa consistent with previous studies in triatomine microbial ecology, locality differences are an important observation for future studies. Geographical heterogeneity in microbiomes of vectors is an important consideration for future developments that leverage microbiomes for disease control.

Leishmania spp. Infection Rate and Feeding Patterns of Sand Flies (Diptera: Psychodidae) from a Hyperendemic Cutaneous Leishmaniasis Community in Panamá.

American cutaneous leishmaniasis (ACL) is a common and important vector-borne parasitic zoonosis in Panamá. Here, we study Leishmania spp. infection rates and blood-feeding patterns among common sand flies in Trinidad de Las Minas, a rural community with hyperendemic ACL transmission, and where a deltamethrin fogging trial was performed. Sand flies were collected from April 2010 to June 2011 with light traps installed inside and in the peridomicile of 24 houses. We restricted our analysis to the most abundant species at the study site: Lutzomyia trapidoi, Lutzomyia gomezi, Lutzomyia panamensis, Lutzomyia triramula, and Lutzomyia dysponeta. We detected Leishmania spp. infection in sand flies by polymerase chain reaction (PCR) amplification of the internal transcribed spacer region 1 (ITS-1) in pooled females (1-10 females per pool). Host species of engorged sand flies were identified using a cytochrome b PCR. From 455 sand fly pools analyzed, 255 pools were positive for Leishmania spp., with an estimated infection rate (confidence interval) of 0.096 [0.080-0.115] before the deltamethrin fogging which slightly, but not significantly (P > 0.05), increased to 0.116 [0.098-0.136] after the deltamethrin fogging. Blood meal analysis suggested that pigs, goats, and birds were the most common sand fly blood sources, followed by humans and domestic dogs. DNA sequencing from a subsample of ITS-1 positive pools suggests that Leishmania panamensis, Leishmania naiffi, and other Leishmania spp. were the parasite species infecting the most common vectors at the study site. Our data confirm an association between sand fly species, humans, domestic dogs, and pigs and Leishmania spp. parasites in rural Panamá.

Malaria infection rates in Anopheles albimanus (Diptera: Culicidae) at Ipetí-Guna, a village within a region targeted for malaria elimination in Panamá.

The Panamá Canal construction encompassed one of the first examples of malaria elimination. Nevertheless, malaria has uninterruptedly persisted in Native American populations living within a few kilometers of the Panamá Canal. Here, we present results from a monthly longitudinal study (May 2016 to March 2018), whose goal was to quantitatively describe seasonal patterns of Plasmodium spp. infection in Anopheles albimanus Wiedemann, and its association with environmental covariates, at Ipetí-Guna, a village within a region targeted for malaria elimination in Panamá. To detect Plasmodium spp. infections we employed a standard nested PCR on DNA extracts from mosquito pools of varying size, which were then used to estimate monthly infection rates using a maximum likelihood method. The infection rate estimates (IR) were analyzed using time series analysis methods to study their association with changes in rainfall, temperature, NDVI (a satellite derived vegetation index), malaria cases and human biting rates (HBR). We found that mosquitoes were infected by Plasmodium vivax mainly from September to December, reaching a peak in December. Time series modeling showed malaria IR in An albimanus increased, simultaneously with HBR, and IR in the previous month. These results suggest that elimination interventions, such as mass drug administration, are likely to be more effective if deployed from the middle to the end of the dry season (March and April at Ipetí-Guna), when the likelihood of malaria infection in mosquitoes is very low and when curtailing human infections driving infections in mosquitoes can reduce malaria transmission, and increase the chance for elimination.